The Orange County Water District (OCWD) owns 2,150 acres behind Prado Dam in Riverside County, CA. The Prado Wetlands are the largest stand of forested, riparian habitat remaining in coastal Southern California.

The Prado Wetlands has been at the forefront in advancing treatment wetland technology since it began operations in July 1992. Our 3-mile hike with the water district’s habitat restoration manager, Bonnie Nash took us through 465 acres of constructed wetlands.

The OCWD leases hunting rights on their property to several local duck clubs. Yes, it’s kind of a bizarre set-up but hunting, when done properly, helps keep the whole wetland area balanced and healthy.

Not open to the public, the OCWD offers only 4 tours during the spring and summer months.

Bird Box

The OCWD owns 2,150 acres behind Prado Dam, including nearly 465 acres of the largest constructed wetlands in Southern California. In addition to providing an ideal habitat for birds, the wetlands effectively reduce nitrogen levels in Santa Ana River water.

We were very fortunate to spot a black bear during our hike.

…so back the f*ck up & stay clear.

Modified from a series of duck hunting ponds located adjacent to the Santa Ana River in 1992, the Prado Constructed Wetlands (PCW) is a system of treatment ponds designed to remove nitrate and emphasize the characteristics of natural wetland ecosystems.

This productive and rare ecosystem supports more than 311 species of vascular plants, seven species of amphibians, 13 species of reptiles, 47 breeding bird species, 11 raptor species and 23 mammal species.

“A network of levees, weirs, and conveyance piping control water flow through the ponds where it undergoes sedimentation, assimilation, adsorption, and denitrification treatment processes, all of which are specifically designed to remove nitrogen and other pollutants from tertiary-treated wastewater in the Santa Ana River. But no typical man-made wetland will do for removing more potent contaminants like medical drugs and synthetic compounds. To help remove those, scientists built three different ponds where water is subjected to sunlight and bacteria that help to degrade chemicals including antibiotics, anti-inflammatory drugs and sex hormones. On average, Prado wetlands removes approximately 30 tons of nitrate a month.” – Source

Owl Spotting

Using binoculars to get a closer look, you can almost make out the outline…

…of the baby owls staring back at you.

The Prado Dam was built by the U.S. Army Corps of Engineers in 1941 in response to periodic flooding of the 96-mile Santa Ana River inundating large areas of Orange County. Downstream of the dam, OCWD actively manages recharge by diverting river water into a series of percolation basins. The Prado Dam & basin is a crucial part of a mammoth flood-control system that protects more than 3 million people in San Bernardino, Riverside and Orange counties. Prado is hardly a household name in Southern California, where more high-profile wetlands — Ballona, south of Marina del Rey; Bolsa Chica, in Huntington Beach; and, in San Diego County, Batiquitos Lagoon in Carlsbad — historically have grabbed headlines.

Bird Trax

Prado is well-known among birders and environmentalists in the Inland Empire because of its size and importance in an area where new housing developments sprout on former dairy farms and other open land.

The evil Arundo donax, an invasive cane that grows up to 20 feet, hogs water and chokes out native plant life along the Santa Ana River and Prado basin. The OCWD relies on a network of contractors and volunteers to keep the non-native plant in check. The OCWD restores native habitat by planting 10,000 Mulefat tree seedlings in the Prado Basin annually as mitigation for conserving water behind Prado Dam. Mulefat is a large woody shrub with intricate branching that affords birds, including the endangered Least Bell’s Vireo, multiple sturdy nest opportunities.

Meandering waterways lined with trees and vegetation are becoming scarce. The state has lost an estimated 90 percent of these areas, known as riparian corridors.

A peek at Mill Creek, which runs through the property that the OCWD owns and manages.

The endangered Least Bell’s Vireo, a shy, small, gray songbird found only in California’s diminishing wetlands, is recovering in Southern California due to years of habitat restoration and cowbird trapping at Prado Basin in the Chino-Corona area.

The cowbird has a nasty habit of laying its eggs in other birds’ nests and leaving the hatching and rearing to others. But when cowbirds choose the nests of the endangered Least Bell’s Vireo, the Vireo often abandons its nest, leaving the cowbird egg and its own eggs to perish.

Black male cowbirds are used to lure the brown females into the traps. The slit on top allows the birds to slip right through the slot on their way in but makes it nearly impossible for them to escape. The females are then collected and destroyed which helps protect the eggs of the endangered Least Bell’s Vireo.

Hunting blinds are used during the hunting season and can be found throughout the property.

The constant noise of guns being fired at the neighboring shooting range didn’t seem to bother the birds next door.